The purpose of the proposed study is to increase our understanding of how the motor cortex controls movement and subsequently to contribute toward the better treatment of human motor dysfunctions. During the past grant years, we have shown that the motor cortex receives peripheral inputs directly from the thalamus and not through the sensory cortex. We have already shown there are cortical efferent zones within the motor cortex which control contraction of individual muscles, hence the motor cortex and the periphery are connected by the simplest loop circuit. During the coming years, we plan to elucidate the functional significance of various inputs converging into the motor cortex. This will be done by delivering microstimulation to various parts of the central nervous system and examining the effects using the cortico-peripheral loop circuit. The study will hopefully explore further insights of the motor cortex and yield knowledge which will be applicable to the treatment of the patients.